Processing photosensitive materials such as photographic film typically involves multiple steps such as developing, bleaching, fixing, rinsing, and drying the film. Because performance of these steps is well-suited for mechanization, various systems have been designed to convey long strips of film through a series of stations. Each station contains a liquid appropriate to the step to be performed at that station, with the differing liquids contacting the filmstrip sequentially as it is conveyed through the series.
The uniformity and overall quality of the processing operation is dependent upon a number of factors, including the precision with which the liquids are applied to the filmstrip, the integrity of the chemicals used, and the effectiveness of the means by which the filmstrip is protected from abrasions or other damage as it passes through the stations. U.S. Pat. No. 4,327,987 to Friar, et al., for example, discloses a mechanized processor designed to improve the transverse and longitudinal uniformity of the processed product. The processor uses a foraminous sheet of stainless steel screening positioned above the filmstrip to spread a layer of developing solution evenly across the film. The developing solution flows down a ramp until it pools on the film in an area adjacent the screen. As the film travels through the applicator the pool is compressed between the film and screen and forced away from the center of the filmstrip and toward the edges.
U.S. Pat. No. 4,332,454 to Hensel, et al. describes an applicator assembly designed both to coat the filmstrip uniformly with processing fluid and to clean its surface in a relatively gentle manner. The applicator includes an open-celled scrubber pad similar to a sponge positioned above and pressed against the film to be processed. As the film moves through the applicator, developing fluid is pumped through the scrubber pad to form a thin layer between the pad and filmstrip. Oscillation of the scrubber pad helps disperse the fluid across the entire width of the filmstrip as it removes unwanted particles. According to the Hensel, et al. patent, abrasions to the film are lessened in relation to prior systems because the pressure of the scrubber pad against the film is decreased.
While the above-mentioned film processors represent advances over traditional apparatus, a need remains for an automated system capable of providing high quality developing while maintaining the freshness of the processing chemicals over long periods of time and with intermittent utilization. Such an improved apparatus would be suitable for use in automated film processing systems as described in patent application Ser. No. 07/330,112, which function optimally when service requirements are minimized. In order for these systems to be commercially acceptable, uniform processing with minimal surface degradation of the processed film through scratching or abrading also is necessary.
The invention described in application Ser. No. 07/442,193 provides a substantially closed processing station designed to disperse chemicals for uniformly coating or otherwise contacting an emulsive or other surface. The station includes opposed chemical chambers, each of which is covered with a perforated film and, optionally, a mesh or screen-like material, between which materials the photographic print paper or film or other substrate passes. Liquid chemical solutions, mixtures, or suspensions pass into the upper chamber through a central opening and from the chamber through the perforated film onto the film surface or onto the upper screen. The liquid then passes through the upper screen if such is present and is dispersed uniformly across the substrate surface.
As the chemicals enter the upper chamber and press against the upper film it distends about its center, ensuring contact between the perforated film (or the mesh or screen) and the photographic film or other material moving through the station while minimizing the pressure on (and resulting abrading of) the substrate's surface. Excess chemicals continuously puddle beneath and beside the processed material on the lower screen to reduce friction between the material and the lower chamber. Because the station is virtually sealed from the surrounding atmosphere by the close fit between the matched peripheries of the upper and lower chambers, little degradation of the processing chemicals occurs as a result of exposure to air, even after extended periods of nonuse. Furthermore, the small volume of chemicals required to fill the processing station allows the station to be flushed quickly and with a similarly small volume of chemicals and ensures that most of the fluids in the apparatus are in its chemical reservoir rather than in processing trays or tanks if operation is interrupted.